#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/wait.h>

int main()
{
    pid_t id =fork();
    if(id==0)
    {
        //child
        printf("before: i am a process, pid: %d,ppid: %d\n",getpid(),getppid());
        sleep(5);
        //这类方法的标准写法
        execl("/usr/bin/ls","ls","-a","-l",NULL);
        printf("after: I am a process ,pid: %d, ppid:%d\n",getpid(),getppid());
        exit(0);
    }
    //father
    pid_t ret=waitpid(id,NULL,0);
    if(ret>0)
        printf("wait success,father pid:%d,ret id: %d\n",getpid(),ret);
    sleep(5);
    return 0;
}
